The Promise of Space

In this excellent book, Arthur C. Clarke makes his case for why the exploration of space is so fascinating to human imagination, as well as being important to civilization. Logically structured by time, from the earliest flights of fancy to the efforts of the Space Age to contemplation of the future, and by space, from the confines of our home world to the neighboring planets to the stars beyond, the book makes for compelling reading. It's also gorgeously illustrated, including nearly ninety breathtaking black-and-white plates and draftsman-precision diagrams. Clarke's writing is clear and literary, deftly describing scientific and technical concepts while making a general point about space travel and somehow throwing in references to classic literature. It's obvious he's given this some thought!

Published in 1968, the same year Clarke and Stanley Kubrick's collaboration 2001: A Space Odyssey hit the theaters, and just prior to any humans leaving Earth orbit, it is tempting to snicker at inaccuracies we find from our vantage point nearly a half-century in the future. But I found this to be one of the most fascinating aspects of reading this book. It's like a time capsule. This is how people, at least visionary thinkers like Arthur C. Clarke, viewed space in 1968. Naturally, discussion of Apollo dominated the middle of the book, but I loved reading this, placing myself in his time, on the verge of mankind's greatest leap, eager to join him in being optimistic about going beyond.

One item in particular that impressed me was the hint of the then-future Voyager missions. Clarke makes references to missions of this name, but clearly they were still on the drawing board, and their objective was a more modest exploration of Mars. In another spot, not identified with Voyager, Clarke describes the concept of a gravity assist, giving three examples of such a maneuver at Jupiter: 1) an escape out of the plane of the Solar System, 2) an escape of the Solar System but still within its plane, and 3), a total arrest of orbital speed with respect to the Sun, plunging the spacecraft into it. I found this interesting since, besides the small detail of using Saturn instead, Voyagers 1 and 2 did end up using the first two of these maneuvers, more or less, a dozen years after the book was published. The unused third option is intriguing. Maybe this is how we'd send our refuse into the Sun.

In his table of Solar System objects, Pluto is listed with mostly question marks. In particular, its diameter is guessed to be 4000 miles, its mass and gravity unknown, and its atmosphere to be "none." Thanks to New Horizons encounter in 2015, we now know these values - it's a good bit smaller at 1475 miles, and it has an atmosphere! What an exciting time to be alive, when, in addition to finding out this basic information, we have managed to resolve a fuzzy point of light into landscapes of snow fields and jagged ice mountains, not to mention gathering clues for how the Solar System was formed. This is just one fulfillment, out of many to come, of the Promise of Space.